Enthalpy relaxation of glassy glycerol prepared by rapid liquid quenching

Comparative Investigation by Two Analytical Approaches of Enthalpy Relaxation for Glassy Glucose, Sucrose, Maltose, and Trehalose

“…The logarithm of eff (t) in addition to the of supercooled liquid becomes proportional to 1/TS c for a glassy system (23,24). Likewise, increasing eff (t) by enthalpy relaxation has also been experimentally presented by decreasing the excess enthalpy (⌬H ϱ − ⌬H relax ) (3,25,26) as follows,…”

“…An alternative approach to describe the enthalpy relaxation process based on the cooperative rearrangement region (CRR) model proposed by Adams and Gibbs exists (23,24). The original form is expressed by Eq.…”

“…Equation (3) has often been used in order to describe the temperature dependence of the molecular relaxation time in the supercooled liquid state. However, it has also been extended to describe the enthalpy relaxation process in the glassy state (23,24). In this extended model, when enthalpy relaxation proceeds during isothermal aging, it is assumed that the molecular numbers involved in the CRR [Z in Eq.…”

“…where (⌬H ϱ − ⌬H relax ) is the enthalpy deviation from the equilibrium, and eff (t) is defined namely as the effective enthalpy relaxation time (3,(23)(24)(25)(26). The logarithm of eff (t) in addition to the of supercooled liquid becomes proportional to 1/TS c for a glassy system (23,24).…”

“…The Kohlrausch-Williams-Watts (KWW) formula approach (4-13) expresses the stretched exponential decay by assuming a special type of distribution of the relaxation time. The second approach is an extended Adam-Gibbs approach, based on decreasing the configurational entropy (S c ) with aging (3,(23)(24)(25)(26). Other approaches such as the ToolNarayanaswamy-Moynihan equation (22) seem to have some difficulty in the actual application; however, the theory is worth considering.…”